Self-inflating cushions or pads are well known. A leader in this field is Cascade Designs, Inc., maker of the THERM-A-REST(copyright) brand self-inflating mattress pad as well as numerous others based upon the same or similar technology. This technology uses a slab of open cell foam bonded between two flexible sheets of material that are in turn bonded to each other at the perimeter of the slab. The result of this construction yields a fluid impervious enclosure wherein the slab acts as a tensile element to resist uncontrolled shape deformation of the enclosure. In other words, the enclosure retains the shape of the slab when the enclosure is pressurized above atmospheric pressure since the bonded foam resists the tendency of the sheets to go non-planar.
Occasionally during use, such pads are punctured, which results in the loss of air in and collapse of the enclosure. Because the open cell foam is selected for its appropriateness as a tensile element, it does not perform well when in compression. As a consequence, the pad will fail to perform as intended until the enclosure is again sealed from the environment.
In the field of outdoor recreation, the environment in which an enthusiast will use a self-inflating pad varies widely from season to season, and even during a season. As is well known by people serious about outdoor adventure, weight is of high concern. Thus, having sufficient protection from the environment without having unnecessary weight is considered an advantage.
The invention is directed to a multiple chamber inflatable body that combines both a self-inflating chamber or compartment and a second chamber or compartment. The second chamber may be constructed to removably receive a resilient member, to permanently retain a resilient member, or to exhibit self-inflating properties. By this invention in its various embodiments, benefits inherent in a self-inflating style ground pad and a conventional self-supporting pad can be attained.
All embodiments of the invention comprise a first chamber defined by a first outer flexible panel having an outer surface, an inner surface and a periphery superposed upon an intermediate flexible panel having a first or upper surface, a second or lower surface and a periphery. A common portion to the first outer flexible panel is substantially secured to the intermediate flexible panel to thereby create the first chamber. This first chamber is preferably fluid impervious so that gas (included in the definition of xe2x80x9cfluidxe2x80x9d) once in the chamber cannot escape without user intervention.
A resilient member is preferably disposed in the first chamber, although any member having extension counteracting properties (tensile properties) as well as compressibility properties is sufficient. This first resilient member is preferably bonded to the inner surface of the first outer flexible panel and the first surface of the intermediate flexible panel so as to act as a tensile member when the chamber has positive pressure. To the extent possible, it is also preferable to bond the perimeter of the first resilient member to either panel. This form of a self-inflatable body is found in U.S. Pat. Nos. 4,624,877, 5,282,586, 5,552,205 and 5,705,252, the disclosures of which are incorporated herein by reference.
In various embodiments, the first chamber is formed by substantially securing the first outer flexible panel to the intermediate flexible panel, however, the first panel and/or the intermediate panel is/are modified to include at least one orifice through which fluid may ingress and egress without user intervention or control. The orifice may be located in either panel, or at the bonded interface between the first panel and the intermediate panel.
By incorporating a user operable valve at the orifice that is in fluid communication with the first chamber and the environment, a user can control the state of the first chamber. Thus, when the valve is opened, air from the environment is drawn into the first chamber by the partial vacuum created by the expanding foam until equilibrium is reached, whereafter the valve is closed. When the valve is again opened and the first chamber compressed, air is expelled until the valve is again closed, whereafter the compressed state of the first chamber is maintained.
In addition to the presence of a first chamber, the invention also includes a second chamber as previously mentioned. The second chamber is defined by a second outer flexible panel having an outer surface, an inner surface and a periphery superposed upon the intermediate flexible panel. A common portion to the second outer flexible panel is selectively secured to the intermediate flexible panel to thereby create the second chamber.
A feature of the second chamber of a preferred embodiment is the lack of an overall fluid imperious structure. Preferably, the second chamber has unsecured a sufficient portion of its perimeter as defined by the common periphery of the second and intermediate panels so as to removably receive a second resilient member. One or more closure elements may be provided to prevent the unintentional dislocation of the second resilient member from the second chamber. In alternative embodiments, a non-removable resilient member (unbonded) as well as a bonded resilient member are employed, and are considered within the scope of the invention.
Contrary to the preceding paragraph, yet another alternative embodiment calls for the incorporation of a fluid impermeable second chamber. Here, the second chamber and second resilient member combination is created according to that of the first chamber and resilient member combination, resulting in a fluid impermeable chamber. Similarly, the second resilient member is preferably substantially bonded to the inner surfaces of the second chamber and a valve is preferably present to regulate the chamber volume. The valve may couple the second chamber to the environment or to the first chamber.
In any of the previously described embodiments, the nature of the resilient members can be varied. While best results for the first chamber pad have been achieved using open cell foam pads, alternatives include fibrous batting Similarly, while best results for the second chamber pad have been achieved using closed cell foam resilient members, alternatives include non-cellular film sheets, thermoformed camping mats, and insulating panels or rigid insulating slats.
In any of the previously described embodiments, the nature of the flexible panels and the methods for bonding the resilient member to the panels can be varied. In one embodiment, the first panel is constructed from polyester fabric that is coated on at least one side with a thermoplastic such as polyurethane, as is the upper surface of the intermediate panel. If the second resilient member of the second chamber is also be bonded, then at least one surface of the second panel is coated with a thermoplastic such as thermoplastic polyurethane, as is the lower surface of the intermediate panel. Textiles are not necessary to execute the present invention. Laminates of polyurethane films or other polymeric films may also be used for one or more of the panels. In other embodiments, one or more layers of a radiant thermal barrier are incorporated into one or more panels. These layers include aluminized skins such as Mylar, or insulating vacuum panels.